Iridium-catalyzed addition of methanol to terminal alkynes

Konkol, Marcin; Schmidt, Harry; Steinborn, Dirk

doi:10.1016/j.molcata.2007.01.001

Cited by 12 publications

(6 citation statements)

References 33 publications

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“…It is noteworthy that although the presence of two C-C triple bonds in compound FcC"CCSC"CH 1 would allow the addition of one alcohol molecule to each alkyne group or a double addition to the same C"C bond, only the formation of compounds 2 has been observed even using a big excess of alcohol or base and variations in the temperature and reaction time. This fact is in contrast with the reports on double hydroalkoxylation [5,6].…”

Section: Resultscontrasting

confidence: 98%

“…Nucleophilic addition to terminal alkynes are expected to follow the anti-Markovnikov's rule while the transition-metal-catalyzed reactions may give either Markovnikov or anti-Markovnikov adducts. Thus, recently it has been reported that the addition of MeOH to different non-functionalized terminal alkynes RC"CH (R = H, n Pr, n Bu, Ph, HC"C(CH 2 ) 4 ) yields to Markovnikov derivatives and only in the case of hex-1-yne and hept-1-yne antiMarkovnikov products are observed [5]. It is noteworthy that although the presence of two C-C triple bonds in compound FcC"CCSC"CH 1 would allow the addition of one alcohol molecule to each alkyne group or a double addition to the same C"C bond, only the formation of compounds 2 has been observed even using a big excess of alcohol or base and variations in the temperature and reaction time.…”

Section: Resultsmentioning

confidence: 99%

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Formation of multifunctional ligands by nucleophilic addition of alcohols and thiols to the alkyne groups in compound C5H5FeC5H4CCSCCH: Reactivity studies

Delgado

Hernández

Nievas

et al. 2010

Journal of Organometallic Chemistry

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Section: Resultscontrasting

confidence: 98%

Section: Resultsmentioning

confidence: 99%

Formation of multifunctional ligands by nucleophilic addition of alcohols and thiols to the alkyne groups in compound C5H5FeC5H4CCSCCH: Reactivity studies

Delgado

Hernández

Nievas

et al. 2010

Journal of Organometallic Chemistry

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“…The same high diastereoselectivities and high E/Z-ratios were detected in both series, using D-ribose 29 as The intermolecular addition of alcohols to terminal and activated alkynes has been reported before [133][134][135][136][137][138] and has been used extensively in radical cyclization of β-alkoxyacrylates [139][140][141][142][143][144][145][146][147][148][149][150][151][152][153][154], in reductive cyclizations of β-alkoxyacrylates (Maitotoxin total synthesis [155][156][157][158][159]) and palladium-catalyzed cyclization in the presence of CO [160]. For an overview of the application of alkynes in organocatalysis see reference [161].…”

Section: -54 (R'=h R''=h Oh) 56 (R'=ch 2 Oh R''=oh)supporting

confidence: 70%

Organocatalyzed Glycosylation Reactions of Carbohydrates

Mahrwald¹

2015

SpringerBriefs in Molecular Science

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Several different organocatalyzed glycosylation processes of carbohydrates will be discussed. The results clearly support the concept of the application of unactivated and unprotected carbohydrates in glycosylation processes. By generating hydrogen bridges, which are working during the reaction, the configuration at the anomeric carbon atom can be controlled. Extremely high degrees of stereoselectivities were obtained, depending on the configuration of the carbohydrates deployed.

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“…1). This method compares well with the earlier procedures catalyzed by Hg, 6,7) Pd, [8][9][10] Pt, 9,11,12) Au, [13][14][15][16][17][18][19][20][21][22] Ir [23][24][25][26] and Zn.…”

supporting

confidence: 72%

A Fluorinated Cobalt(III) Porphyrin Complex for Hydroalkoxylation of Alkynes

Ushimaru

Nishimura

Iwatsuki

et al. 2017

CHEMICAL & PHARMACEUTICAL BULLETIN

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A fluorinated cobalt(III) porphyrin complex [Co(TPFPP)- (Fig. 1). This method compares well with the earlier procedures catalyzed by Hg, 6,7) Pd, [8][9][10] Pt, 9,11,12) Au, [13][14][15][16][17][18][19][20][21][22] Ir [23][24][25][26] and Zn. 27)The active pentafluorophenylated Co III catalyst 1a was developed by structural modification of 1b used previously for alkyne hydration 2) (Fig. 1). Reaction of tetrakis(pentafluorophenyl) porphyrin (H 2 TPFPP) and cobalt(II) acetate 28) followed by aerobic oxidation in the presence of HNTf 2 and recrystallization from a mixture of chloroform, ethanol, and hexane afforded 1a in 67% yield. X-Ray structural analysis of 1a indicated that (1) the cobalt center adopts octahedral geometry, with porphyrin ligand in the equatorial positions and ethanol in the apical positions (Fig. 2); (2) Figure S1(a)].The catalyst 1a was found to be more reactive than 1b in the hydroalkoxylation of phenylacetylene (2a) with methanol (Table 1, entries 1 vs. 7). When a mixture of 2a (2.0 mmol), 1a (0.05 mol%), and HNTf 2 (0.18 mol%) in methanol (0.9 mL, 11 equiv) was heated at 70°C for 4 h under aerobic conditions, acetal 3a was obtained in 97% yield (entry 1).29) The initial turnover frequency (TOF) was 4000 h −1 (t=12 min). This value is comparable to those of gold catalysts and higher than those of catalysts based on other metals (entry 2). 30) Hydroalkoxylation of 2a in the absence of HNTf 2 required higher catalyst loading (entries 3 and 4). The reaction proceeded under N 2 atmosphere, but yielded 3a in a lower yield than that under air (entry 5 vs. entry 1). Double hydroalkoxylation of 2a at 27°C (room temperature) afforded acetal 3a in 97% yield (entry 6). Co III TPPCl [TPP=5,10,15, porphyrin] was less reactive than 1a and 1b (entry 8 vs. entries 1 and 7). The reaction hardly proceeded with analogous metal complexes such as Fe III TPPCl or Mn III TPPCl under otherwise identical conditions (entries 9 and 10).* To whom correspondence should be addressed. e-mail: h_naka@nagoya-u.jp

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Iridium-catalyzed addition of methanol to terminal alkynes

Cited by 12 publications

References 33 publications

Formation of multifunctional ligands by nucleophilic addition of alcohols and thiols to the alkyne groups in compound C5H5FeC5H4CCSCCH: Reactivity studies

Formation of multifunctional ligands by nucleophilic addition of alcohols and thiols to the alkyne groups in compound C5H5FeC5H4CCSCCH: Reactivity studies

Organocatalyzed Glycosylation Reactions of Carbohydrates

A Fluorinated Cobalt(III) Porphyrin Complex for Hydroalkoxylation of Alkynes

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